1. Field of the Invention:
This invention relates to high power gas lasers. It is specifically concerned with a pulsed laser operating at high pressure under static gas conditions or with gas flow through the laser cavity while modulating the glow discharge by independent pulsing means.
2. Description of the Prior Art:
Laser systems have been developed using a double discharge to supply initiatory free electrons to the main discharge gap by means of a first discharge and then subsequently pulsing the gap to develop a high energy main glow discharge. The advantages of this type of operation include stabilization of the glow discharge without arcing and providing for discharge paths such that any arcing during the preliminary discharge is outside the useful volume of the laser cavity. The double discharge form of excitation has also made possible excitation of larger volumes of gas.
In a double discharge system various electrode geometries are possible. The preliminary discharge can be across a separate pair of electrodes, producing free electrons in the gap between another pair of electrodes between which the main discharge then takes place. Or a three electrode geometry is possible in which one electrode is common to both discharges.
However the common feature of a double discharge excitation system regardless of the particular electrode geometry is the interaction or dependency between the two discharges. The initial or preliminary discharge which takes place is not independent of the main discharge. The interdependence of the two discharges requires the switching or modulating of the total power into the discharge gap. Thus the main discharge gap is pulsed which requires the switching of kilovolt potentials in submicrosecond time periods. Such modulation of power in the discharge gap requires expensive pulsing equipment including a power supply and switching means such as a thyratron.